I don't have the time for another fic or snippet or whatever but I had an idea. Drummer!Steve, right? And a common thing I'm seeing in that is that Gareth knows and is the one that taught him or got him started on the basics or told him where to go for gear... But what if... Envision with me...
Steve Harrington played the drums in middle school. He was a dramatic band kid and sports-type hybrid. He's the only drummer his school has and he's really good so administration makes it work with sports things cause sports & arts grants would really help the school and looks good at fundraisers so they need him but other kids think it's special treatment cause the Harrington name. Anywho, Steve is starting 8th grade and administration is in a bit of a tizzy over finding a new drummer for band stuff to replace him after graduating cause no one else wants to pick it up.
Enter Gareth. He's technically one of the flute (or violin Idk which I'd prefer for this) kids but Steve catches him playing around with his set after school one day. Steve convinces the kid to learn how to play drums for the rest of the year and through summer so next year he can try out for band again and take over as drummer. Gareth takes it but doesn't want anyone to know he's getting all buddy-buddy with Harrington cause he JUST got the guys who were in the talent show last year with a metal song to notice him and include him in their little tight-knight group and he WILL NOT let Steve Harrington of all people ruin that for him.
Fast forward a few years and Eddie survived the Upside Down, the rest of Corroded Coffin got read in while helping take care of the aftermath. Everything is okay and good and over now. But Gareth has a kind of fucked up hand. Jason Carver injured it and it never managed to heal quite right in the everything that came after. Thanks to government cover-up medical care there's a way to fix him up but it'll take time and as Eddie and the rest of Corroded Coffin keeps lamenting, C.C. has gigs to play and demos to record and- and- and- and Gareth asks if Eddie will shut up if he can come up with a replacement drummer.
Eddie and the band are hesitant until Gareth admits it's the guy who taught him to play and the guy is probably still just as good, if not better than him. So they have to promise to not replace him with the guy if he can convince him to help them out. Corroded Coffin swears on Dustin's mother (Claudia Henderson is a goddess amongst mortals and once she got read in put Joyce Byers to shame in her audacity dealing with the government bullshit) to not replace Gareth if he can bring this mystery drummer by next practice.
Gareth lets them into the garage next week for practice telling them his temp will be there any minute. As everyone else is finishing setting up a burgundy BMW pulls up, not unusual cause sometimes Steve will come by practice with snacks and just hang out while killing time between work and dealing with the kids. And the Steve that steps out of the BMW has an armful of food that's probably delicious but Freak notices that the hand that lifts for his signature little finger waggle of a wave has something else in it. He turns to Gareth with a giant grin on his face who turns bright red and grits out for him to not say a word.
"Heya guys, hear you need a drummer?"
Eddie's face falls. "No." He desperately turns to Gareth, "Please tell me this is just another very niche dream of something that will never happen to me in my waking hours." Gareth can't.
And Idk, Jeff and Freak don't quite believe that he's that good cause it's been a few years and Steve plays one of their originals making Eddie practically drool but everyone else is too flabbergasted to give him shit.
And somewhere between practices and Gareth finally letting himself be adopted by Steve (partially cause he is peak older sibling vibes but also it drives Eddie mad the guy he's falling for basically being one of his best friend's older brother. Idfk) Eddie and Steve figure their shit out and start dating. Maybe with a jealous Dustin cause HE adopted Steve first, how dare Gareth come and steal his rightfully shanghaied older sibling/best friend?
That's all I got. Someone take this and go crazy.